Equity-Accounted Investments And Other Long-Term Assets (Summary Of Other Long-Term Asset) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Mar. 31, 2018	Jun. 30, 2017
Schedule Of Equity And Held To Maturity Investments [Line Items]
Total equity investments	$ 235,361	$ 26,317
Total held to maturity investments	9,769
Long-term portion of payments to agents in South Korea amortized over the contract period	19,447	17,290
Policy holder assets under investment contracts (Note 8)	701	627
Reinsurance assets under insurance contracts (Note 8)	224	191
Other long-term assets	5,683	5,271
Total other long-term assets	271,185	$ 49,696	[1]
Cell C [Member]
Schedule Of Equity And Held To Maturity Investments [Line Items]
Total equity investments	$ 206,970
Equity-accounted investments, ownership percentage	15.00%	15.00%
MobiKwik [Member]
Schedule Of Equity And Held To Maturity Investments [Line Items]
Total equity investments	$ 28,391	$ 26,317
Equity-accounted investments, ownership percentage	12.00%	12.00%
Cedar Cellular [Member]
Schedule Of Equity And Held To Maturity Investments [Line Items]
Total held to maturity investments	$ 9,769
Equity-accounted investments, ownership percentage	7.625%	7.625%
Interest rate	8.625%	8.625%
Maturity year	2022	2022

[1] Derived from audited financial statements